turns out there is already an implementation from darktable. but i still feel that the CMY adjustments are more straightforward.

as of now it’s still a toy. but i see potential 😉

pt.3
1️⃣ Convert the scan into film density data
2️⃣ Simulate different CMY light intensities during exposure
3️⃣ Calculate the final reflectance after paper development

pt.2
You can’t remove the mask with just white balance tools.
Curves can work, but it’s tedious and hard to master.
In the darkroom, artists would simply adjust the CMY light intensities to color-correct precisely. So, why not simulate that with an algorithm?